Update versions to 6.0.0.beta

Author: estolfo

Diff for: elasticsearch-model/lib/elasticsearch/model/version.rb

@@ -1,5 +1,5 @@
 module Elasticsearch
   module Model
-    VERSION = "6.0.0.alpha1"
+    VERSION = "6.0.0.beta"
   end
 end

Diff for: elasticsearch-persistence/lib/elasticsearch/persistence/version.rb

@@ -1,5 +1,5 @@
 module Elasticsearch
   module Persistence
-    VERSION = "6.0.0.alpha1"
+    VERSION = "6.0.0.beta"
   end
 end

Diff for: elasticsearch-rails/lib/elasticsearch/rails/version.rb

@@ -1,5 +1,5 @@
 module Elasticsearch
   module Rails
-    VERSION = "6.0.0.alpha1"
+    VERSION = "6.0.0.beta"
   end
 end